// Copyright 2024 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package functions

import (
	"fmt"

	"github.com/cockroachdb/errors"
	"github.com/dolthub/go-mysql-server/sql"

	"github.com/dolthub/doltgresql/server/functions/framework"
	pgtypes "github.com/dolthub/doltgresql/server/types"
	"github.com/dolthub/doltgresql/utils"
)

// initVarChar registers the functions to the catalog.
func initVarChar() {
	framework.RegisterFunction(varcharin)
	framework.RegisterFunction(varcharout)
	framework.RegisterFunction(varcharrecv)
	framework.RegisterFunction(varcharsend)
	framework.RegisterFunction(varchartypmodin)
	framework.RegisterFunction(varchartypmodout)
}

// varcharin represents the PostgreSQL function of varchar type IO input.
var varcharin = framework.Function3{
	Name:       "varcharin",
	Return:     pgtypes.VarChar,
	Parameters: [3]*pgtypes.DoltgresType{pgtypes.Cstring, pgtypes.Oid, pgtypes.Int32},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [4]*pgtypes.DoltgresType, val1, val2, val3 any) (any, error) {
		input := val1.(string)
		typmod := val3.(int32)
		maxChars := pgtypes.GetCharLengthFromTypmod(typmod)
		if maxChars < pgtypes.StringUnbounded {
			return input, nil
		}
		truncated, runeLength := truncateString(input, maxChars)
		if runeLength > maxChars {
			return input, errors.Wrap(pgtypes.ErrCastOutOfRange, fmt.Sprintf("value too long for type varying(%v)", maxChars))
		} else {
			return truncated, nil
		}
	},
}

// varcharout represents the PostgreSQL function of varchar type IO output.
var varcharout = framework.Function1{
	Name:       "varcharout",
	Return:     pgtypes.Cstring,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.VarChar},
	Strict:     true,
	Callable: func(ctx *sql.Context, t [2]*pgtypes.DoltgresType, val any) (any, error) {
		v, ok, err := sql.Unwrap[string](ctx, val)
		if err != nil {
			return nil, err
		}
		if !ok {
			return nil, fmt.Errorf(`"varcharout" requires a string argument, got %T`, val)
		}
		typ := t[0]
		tm := typ.GetAttTypMod()
		if tm != -1 {
			str, _ := truncateString(v, pgtypes.GetCharLengthFromTypmod(tm))
			return str, nil
		} else {
			return v, nil
		}
	},
}

// varcharrecv represents the PostgreSQL function of varchar type IO receive.
var varcharrecv = framework.Function3{
	Name:       "varcharrecv",
	Return:     pgtypes.VarChar,
	Parameters: [3]*pgtypes.DoltgresType{pgtypes.Internal, pgtypes.Oid, pgtypes.Int32},
	Strict:     true,
	Callable: func(ctx *sql.Context, t [4]*pgtypes.DoltgresType, val1, val2, val3 any) (any, error) {
		data := val1.([]byte)
		if data == nil {
			return nil, nil
		}
		return t[3].IoInput(ctx, string(data))
	},
}

// varcharsend represents the PostgreSQL function of varchar type IO send.
var varcharsend = framework.Function1{
	Name:       "varcharsend",
	Return:     pgtypes.Bytea,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.VarChar},
	Strict:     true,
	Callable: func(ctx *sql.Context, t [2]*pgtypes.DoltgresType, val any) (any, error) {
		if wrapper, ok := val.(sql.AnyWrapper); ok {
			var err error
			val, err = wrapper.UnwrapAny(ctx)
			if err != nil {
				return nil, err
			}
			if val == nil {
				return nil, nil
			}
		}
		str, err := t[0].IoOutput(ctx, val)
		if err != nil {
			return nil, err
		}
		writer := utils.NewWireWriter()
		writer.WriteString(str)
		return writer.BufferData(), nil
	},
}

// varchartypmodin represents the PostgreSQL function of varchar type IO typmod input.
var varchartypmodin = framework.Function1{
	Name:       "varchartypmodin",
	Return:     pgtypes.Int32,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.CstringArray},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val any) (any, error) {
		return getTypModFromStringArr("varchar", val.([]any))
	},
}

// varchartypmodout represents the PostgreSQL function of varchar type IO typmod output.
var varchartypmodout = framework.Function1{
	Name:       "varchartypmodout",
	Return:     pgtypes.Cstring,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.Int32},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val any) (any, error) {
		typmod := val.(int32)
		if typmod < 5 {
			return "", nil
		}
		maxChars := pgtypes.GetCharLengthFromTypmod(typmod)
		return fmt.Sprintf("(%v)", maxChars), nil
	},
}